1. Field of Invention
This invention relates to systems and methods for controlling specific hues in a color image to adjust selected hues.
2. Description of Related Art
The digital reproduction, transfer or display of various images presently occurs using a variety of devices and systems in a variety of environments. The image may be input into a device, processed in some manner, and then output from the device using a printing technique, for example. In some applications, it may be necessary or desirable to convert the image between the input and the output of one device for the specific purpose of using the converted image data by another device. In other applications, it may be necessary or desirable to convert the input image for some particular application within a device itself. In some applications, it may be desirable or necessary to adjust one or more of the hues in an image.
Various hue adjustment techniques are known. These hue adjustment techniques adjust various colors in various imaging devices. The color adjustment processes performed in such equipment may be analog or digital in nature. U.S. Pat. No. 5,305,094 discloses one such color corrector. The apparatus disclosed in the 094 patent is provided with controls for an operator to select, using a window, one color out of many colors. The group of hues among which a selection can be made advantageously includes the three primary and the three secondary colors.
Moreover, the 094 patent discloses that a separate window can be provided for each of those six colors. Together with a separate window for the narrow-band circuit, a total of at least seven windows can be formed and used in a given picture. The selected color can be adjusted inside the window, and a different color can be adjusted outside of the window. All other hues remain unaffected by a window dedicated to one hue. As a result, the other colors can be color-corrected simultaneously with the selected color in all parts of the picture.
Further, U.S. Pat. No. 5,731,818 describes a method for gamut clipping of an image based on user-defined constraints on lightness and hue. The method disclosed in the 818 patent is performed by defining a color gamut surface of an output device using a gamut descriptor and specifying a search range based on maximum tolerances for lightness and hue changes. The 818 patent describes that, for each input color data point outside the gamut, the data point is mapped to the closest point in a portion of the gamut surface specified by the search range.
FIG. 1 further illustrates other known hue adjustment processes. As shown in FIG. 1, the xe2x80x9cno changexe2x80x9d line represents the before and after hue angles of an original image. Using conventional techniques, a user may vary the original hue angle for every color in the original image to avoid one or more offensive colors. Specifically, the user may either increase the hue angle, or alternatively, decrease the hue angle, for every color appearing in the image, as shown in FIG. 1.
However, a problem with these known hue adjustment devices is that such devices do not allow an undesirable hue in an image to be easily identified and effectively modified by a user. More specifically, the known hue adjustment devices do not allow an operator to easily identify a problem color and modify only that problem color, along with a limited number of other colors closely surrounding the problem color.
Additionally, a further problem arises since a particular device, such as a printer, is capable of producing a set gamut of hues. However, the known hue adjustment devices do not allow a user to take this color gamut into account, in conjunction with effectively eliminating problem colors.
Accordingly, this invention provides systems and methods that more specifically adjust a selected hue in an image.
This invention separately provides systems and methods that selectively control the hue angle in a color image to effectively control undesirable or unproduceable hues by performing hue shifts that alter the rendition of only those colors that have hue angles near the offensive color.
This invention separately provides systems and methods that adjust the hue of a problem color while leaving unchanged the hue of colors distant from the problem color.
This invention separately provides systems and methods that adjust hue in an image while taking into account the color gamut of the device on which the image will be displayed or reproduced.
This invention separately provides systems and methods that provide hue adjustments using relatively simple and inexpensive adjustment techniques.
This invention separately provides systems and methods that provide a hue control that permits greater flexibility and utility.
Various exemplary embodiments of systems and methods of the invention provide an image quality control to selectively alter the color in an image. The systems and methods of the invention may be used in any of a wide variety of devices, including a color copier or scanner, for example. The image to be reproduced or printed is displayed so that the user can observe the image. Based on this observation, the user selects a specific color of the image that is offensive or in some way unacceptable. Illustratively, the selection process may be performed by positioning a cursor on the color of the image that is offensive.
In accordance with the systems and methods of the invention, the hues resulting from the adjustments may be tested to see if the hues are outside the range of colors that can be printed accurately on a target print engine. If the image is outside the range of colors, various alternatives can be offered to arrive at the best possible rendition of the image. Alternatively, a hue shift or a variety of hue shifts can be generated that alter the rendition of only those colors having hue angles near the offensive color.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of the exemplary embodiments.